Revealed: the mystery of stinging water

February 14, 2020

People who have experienced stingy, itchy skin from warm coastal waters might be familiar with some of the theories about what causes it – including sea lice, severed jellyfish tentacles and anemones – but the truth has been an enduring puzzle.

Now, a multidisciplinary team of scientists has revealed the source: deceptively placid-looking upside-down jellyfish, Cassiopea xamachana, which pulse rhythmically in groups of hundreds to thousands of individuals at the bottom of shallow bays, lagoons and mangroves.